Circuit breaker



Oct; 30, 1945. 5 J MiTCHELL- 4 y 2,387,925

CIRCUIT BREAKER- Filed Aug. `.11, 194:5

f3 zz fa/1 i 'BY Patented Oct. 30, 1945 CIRCUIT BREAKER Stanley J.Mitchell, Wilkinsburg, Pa., assigner to Westinghouse ElectricCorporation, East Pittsburgh, Pa., a. corporation of Pennsylvania 14Claims.

The invention relates to circuit interrupters and more particularly tomanually and automatically operable small air circuit breakers forcontrolling and protecting electrical circuits.

An object of the invention is the provision ci" a double-throw circuitbreaker having contact means for controlling either of two circuits; andoperating mechanism manually operable to selectively operate saidcontact means to open or close either circuit and automatically operablein responseto predetermined overload conditions to cause opening of thecontact means. l

Another object of the invention is to provide a circuit breaker of thedouble-throw type wherein a single operating mechanism is operable inresponse to abnormal circuit conditions to cause automatic opening ofeither onevoftwo circuits.

Another object of the invention is to provide a circuit breaker whereinan operating handle is operable in either direction from an openposition to selectively close one or the other of two circuits, saidhandle being operable by areleasable operator in response to overloadsin the closed circuit to effect opening of the closed circuit.

Another object of the invention is to provide a circuit breaker havingan improved operating mechanism which is operable to selectively cics'eone or the other of two circuits and a trip device operable in responseto an overload in the selected circuit to effect automatic opening ofthe breaker.

Another object of the invention is the provision of a circuit breakerhaving an operating mechanism including an operating handle operable toselectively close any one of a plurality of circuits, and having areleasable means controlled by a trip device for causing automaticopening of the selectively closed circuit in response to predeterminedoverload conditions.

Another object of the invention is the provision oi.' an improvedcircuit breaker construction that is simple, reliable in operation andrelatively inexpensive to manufacture. Another object o1 the inventionis the provisionl of a manually and automatically operablecircuitbreaker mechanism oi compact and low-cost construction which isalso usable in a single-throw circuit breaker.

The novel features that are considered characterlstic of the inventionare set forth in the api pended claims. The invention itself, however,both as to structure and operation, together with additional -objectsand advantages thereof, will be best understood from the followingdetailed description of one embodiment thereof when read ApplicationAugust 11, 1943, Serial No. 498,188

(Cl 20G-115) in connection with the accompanying drawing, inwhich: v

Figure l is a vertical sectional view of a circuit breaker embodying theprinciples of the invention, the switch arm being shown closed on one ofthe contacts; y

Fig. 2 is a view similar to Fig. 1, but showing the mechanism in amanually opened position;

Fig. 3 is a vertical sectional view of the breaker showing the mechanismin the tripped open position;

Fig. 4 is a vertical sectional view of the circuit breaker showing theswitch arm in the righthand closed position and,

Fig. 5 is a vertical transverse sectional View through the breaker takensubstantially on line V-V of Fig. 3.

Referring tothe drawing, the' circuit breaker is of double-throwconstruction and is mounted in a housing comprising a base portion Il ofmolded insulating material having side walls i3, and a cover plate l5also of insulating material. The circuit breaker itself comprises ingeneral stationary contacts l1 and I9, movable contacts 2l and 23adapted to cooperate respectively with the stationary contacts Il andI9, operating n mechanism indicated generally at and a trip device 2l.'

The stationary contact I1 is rigidly mounted on a conductor 29 securedto the base I l by means ci a screw 3| and having a portion 33 extendingperpendicularly through an opening in the base li to serve as a terminalconnector for connecting the contact l'lto an electrical circuit. 'Ihestationary Contact I9 is similarly rigidly supported on a conductorsecured by means of a seres/3l to the base. A portion 39 of theconductor S5 projects through the base Il to form a teririnal connectorfor connecting the stationary contact i9 in an electrical circuit. Themovable contacts 2l and 23 are rigidly mounted on opposite sides of theinner end of a U-shaped switch arm 4l (see Fig. 5). Each leg of theswitch arm is provided with a T-shaped projection 43 which engagesgenerally triangularshaped openings 45 in corresponding sides of aU-shaped frame l secured by means of screws 49 to the central portion ofthe base Il. Sup- .ported in the outerends of legs of the frame 4l is apivot pin 5I upon which is pivotally mounted an operating handle 53projecting outwardly through an opening 55 in the cover plate l5. Theinner end 51 of the handle is connected by means of an overcenter spring59 to a pin 6l extending therebetween. The ends of the projections 43 onthe switch Yarm 4l are rounded and are adapted to pivot in the roundedupper corners of the openings 45,

' as indicated at 63 and 65, to open and close the contacts. It will beobvious that with the handle 53-51 in the position shown inFig. 1, thecenter,

line of the spring 59 lies to the left of the pivot point 63 and',therefore, biases the switch arm 4| in a direction to maintain thecontact 2| in engagement with the corresponding stationary contact |1.In order to separate the contact 2| from the contact I1, the handle 53is rotated in a counterclockwise direction (Figi) to the intermediateoff position shown in Ilig. 2. During this movement, the inner end 51 ofthe handle carries the center line ofthe spring 59 to the right of thepivot point 63, at which time the spring 59 biases the switch arm 4| tothe on position (Fig. 2). Due to the flat outer walls of the openings 45or to the engagement vat both. pivot points 63 and 65, the spring 59will maintain the switch arm 4| and the handle 53 in the oi" position inwhich these parts are shown inFig. 2.

Movement of the handle 53 in a clockwise direction from the oil positionwill carry the spring 59 overcenter to the left of the pivot point 63and close the contacts |1-2I with a snap aotion, and if the handle ismoved in a counterclockwise direction from the on position (Fig. 2), thecenter line of the spring 59 will be moved v to the right of the pivotpoint 65 and enect closing of the contacts |9-23 with a snap action. Itwill thus be seen that by moving the handle v 53 in the appropriateIdirection from its neutral position (Fig. 2), the contacts |'|-2| orthe contacts |9--23 may be closed at will.

The handle 53 is adapted to be automatically actuated to its ofiposition from either of its on positions by means of areleasable-actuator l. The actuator 61 is pivotally supported on a pivotpin 69 mounted in the two legs of a U'- shaped bracket 1| (only one legbeing shown) secured by means of a s crew '|3 to the base Ila. Theactuator 61 is biased in a clockwise or opening direction bymeans of acoil spring having one end anchored to the outer end of the bracket 1 I,and the other end hooked in a suitable hole in the actuator 61. Thelatch end 11 of the actuator 61 is normally engaged and releasably heldin its operative position by the trip device 21.

The trip device 21 comprises a bimetal element 19 having one end rigidlysecured' to a conductor 8| which is, in turn, secured by means of ascrew B3 to the base of the housing. The conductor 8| extends through anopening in the end walll of the housing'and serves as a line terminalconnector 82 for connecting the breaker to the supply line of anelectrical circuit. At its free end, the bimetal element 'I9 carries alatch member 85 which engages the latching end l1 of the actuator 61 toreleasably restrainthe actuator in its operative position.

The circuit, through the breaker is completed by a flexible shuntconductor 81 which connects the free end of the bimetal element 19 toone leg of the switch arm 4| which is of conducting material. Onecircuit extends from the terminal 82 through the conductor 8|, thebimetal 19, flexible shunt conductor 81, switch arm 4|, contacts 2l andl1, conductor 29 to the terminal 33. If the switch arm 4| is operated tothe position wherein the contact 23 engages the stationary contact i9,the other circuit will be completed from the terminal 82, through thebimeta'l element 19, conductor 81, switch arm 4|, and contacts 23- I9 tothe terminal 39.

When an overload occurs either in the circuit including the terminal 33or the terminal 39, depending on which of the contacts are closed, thebimetal element becomes heated by the overload currentwand when heated apredetermined amount it deiie'cts toward the left and releases theactuator 61. When the actuator is released, the spring 15 rotates itsharply clockwise. During this movement, the actuator 61 engages aprojection 89 or a projection 9| of a cam on the handle, depending onthe position ofthe handle, and rotates the handle to the on position. Asshown in Fig. 1,the actuator 6l would engage the projection 9| androtate the handle 53 counterclockwise to the ofl" position. If, however,the handle was in its extreme counterclockwise on position so that thecontacts 23|9 were engaged, the actuator 61 would engageY the projection89 and rotate the handle in a clockwise direction to the off position.As previously explained, movement of the handle from either of its "onpositions to the ofi or central position moves the springacross thepivot point 63, or 65, to thereby effect opening movement of the switcharm 4| with a snap action. The mech- :mism is .shown in Fig. 3 in thetripped open posiion.

'The actuator G1 is manually reset following an automatic openingoperation by moving the handle 53 in either direction from the offposition slightly beyond either of the on" positions. Near theextremities of such movement, one of the projections 89 or 9| on thehandle engages the actuator 61 and moves it in a direction to reengagethe latching end 11 thereof with the latch member 85. This movement ofthe handle, as previously set forth, effects closing of the contacts..The desired contacts |1-2i or |9-23 are closed, and the mechanism resetby a single movement of the handle in the proper direction. After themechanism has been reset by movement of the handle in either directionpast either of its on positions, the handle is released and the spring59 returns it to the on position. The spring 59 provides contactpressure for the close'd contacts and also functions to provide quickmake and break for both sets of contacts. It may be noted that when thebreaker is in either of its on positions the actuator 61 is normallyclear of the projections 89-9|. This insures a with the patent statutes,it is to be understood that various changes and modifications may bemade in the structural details thereof without departing from some ofthe essential features of the invention.

I claim as my invention:

l. A circuit breaker for controlling a plurality of circuits comprisinga support frame, a switch member supported on said frame, said switchmemberhaving a plurality of spaced pivots about which it pivots toselectively close said circuits, an operating handle having a neutral"open position and operable in either direction from said open positionto closed positions for selectively closing said circuits, meanscomprising a spring operable by said handle to move said switch memberabout said pivots to selectively elect manual opening and closing ofsaid circuits, a biased member releasable to effect automatic opening ofsaid circuits, and means on said handle engageable .by said releasablemember and operable by said releasable member to automatically actuatesaid handle to open position from either of its closed positions.

2. A circuit breaker for selectively controlling a plurality of circuitscomprising a plurality of sets of separable contacts, a switch memberhaving a plurality of spaced pivots, said switch member being operablefrom an open position about one of said pivots to close one of said setsof contacts and about another of said pivots to close another of saidsets of contacts, operating mechanism for said switch member including amanual handle and an overcenter spring connecting said handle to saidswitch member, said spring being operable by said handleto move theswitch member about said pivots to selectively close and open saidcontacts, biased means releasable to effect automatic opening movementof said handle, means on said handle engageable by said biased meansupon release thereof to actuate said handle to open position to therebycause opening movement of said switch member.

3. A circuit breaker for controlling a plurality of circuits comprisinga pluralityT of stationary contacts, there being a stationary contactfor each of said circuits, a switch member having a plurality' of spacedpivots, movable contact means carried by said switch member, said switchmember being movable about one or the other oi said 1pivots toselectively engage the movable contact means with one or the other ofsaid stationary contacts to close said circuits, operating mechanismincluding an operating handle having a plurality of closed positions andoperable to move said switch arm from a central open position in eitherdirection to selectively close said cuits, and tripping means operablein response to predetermined overload conditions t cause opening of saidmovable contact means and movement of said handle to open position.

4. A circuit breaker for selectively controlling a plurality of circuitscomprising a plurality or" stationary' contacts, a switch arm having aplurality of spaced pivots, movable contacts mounted on said switch arm,operating mechanism including a manual handle for operating said switcharm to selectively engage said movable contacts with said stationarycontacts, a biased member releasable to effect separation of the closedcontacts, and a trip device comprising a thermostatic member heated inresponse to overload current of whichever circuit isclosed and operablewhen heated a predetermined amount to release said biased member.

5. A circuit breaker for selectively controlling a plurality of circuitscomprising a plurality of stationary contacts, a single switch armmovable to engage each of said stationary contacts to selectively closesaid circuits, operating mechanism for said switch arm including anoperating handle for. moving said switch arm in either direction from anopen position to closed said circuits, releasable actuating meansnormally disengaged from said handle and biased to engage and move saidhandle from either oi said closed positions to the open position whensaid means is released, and means operable in response to abnormalcircuit conditions to effect release or" said actuating means.

6. A circuit breaker for selectively controlling a plurality of circuitscomprising a pair of spaced stationary contacts, a switch member movablein either direction from an open position to selectively close saidcircuits, operating mechanism for said switch member including anoperating handle, an overcenter spring connecting said handle to saidswitch member, the same spring being operable by said handle to move theswitch member in opposite directions and Selectively close the circuitsthrough each of said stationary contacts, an actuator normally held infixed position during manual movement of said handle and releasable toactuate said handle in either direction to an open position, and acurrent-responsive trip device operable in response to overload currentsin any of said circuits to release said actuator to thereby eiectmovement or" the switch member in either direction to an open position,said handle being operable to effect opening of said contacts withoutreleasingsaid actuator.

7. A circuit breaker for selectively controlling a plurality of circuitscomprising a pair of spaced stationary contacts, a switch member`operable in either direction from a central open position to selectivelyclose the circuit through each of said stationary contacts, operatingmechanism for said ,switch member comprising an operating handle and oneovercenter spring for operating0 able to a plurality of closed positionsfor selectively closing said circuits, a plurality of spaced pivots forsaid switch member, an operating handle having an open position, saidhandle being movable to a closed position in either direction from saidopen position, an overcenter spring operable by said handle for movingsaid switch member about one or another of said pivots to selectivelyclose said circuits, a cam on said operating handle, a biased memberreleasable to engage said cam and actuate said handle to the openposition to thereby cause automatic movement of the swith member fromeither one of its closed positions to open position, and a trip eviceoperable in response to overload currents in said circuits to releasesaid biased member.

9. A circuit breaker comprising a U-shaped frame, a pair of stationarycontact means, a switch member movably supported in said frame, movablecontact means on said switch member for cooperating with each of saidpair of stationary contact means, operating mechanism for said switchmember comprising an operating handle and an overcenter spring havingone end attached to said handle and the other end connected to saidswitch member, biased actuating means releasable to engage and operatesaid handle to cause automatic opening of said contact means, andcurrent responsive means operable when heated a predetermined amount toinitiate movement of said actuating means, said handle being operable toeffect opening and closing of said contact means without releasing saidactuating means.

10. A circuit breaker having a support frame provided with asubstantially triangular opening, stationary contact means, a switchmember having a substantially at end for engaging said opening formovement therein, movable contact means on said switch member forcooperating with said stationary contact means, operating mechanism foroperating said switch member to open and closed positions comprising anoperating handle and an overcenter spring connecting said switch memberto said handle, an actuator releasable to engage and operate said handleto cause automatic opening of said contact means, and current responsivemeans operable in response to abnormal current conditions to releasesaid actuator.

11. A circuit breaker for selectively controlling either of two circuitscomprising a frame, two sets of contacts, one switch member mountedsolely on said frame and movable to selectively close either set ofcontacts, manual means including a handle separate from said switchmember for` moving said switch member to selectively close said sets ofcontacts, actuating means other than said manual means for causingauto-matic opening of said sets of contacts, and trip means operable inresponse to abnormal conditions in whichthe "open positionand thereby.causing opening of whichever set of contacts is closed, currentresponsive trip means operable in response to overload currents inwhichever circuit is closed to release said trip member and causeautomatic movement of said switch member to said central open position,and said manual means being operable to effect opening of said sets ofcontacts without operating said trip member.

13. A circuit breaker for selectively controlling a plurality ofcircuits comprising a plurality of stationary contacts, a single switcharm having contact surfaces thereon movable to engage said stationarycontacts to'selectively close said cir.;h cuits, operating mechanism forsaid switch arm comprising an operating handle for moving said switcharm in either direction from an open position for closing said circuits,releasable actuating means normally disengaged from said handle and heldin a fixed position when the handle is moved, means biasing saidactuating means to engage and move said handle from either of saidclosed positions to the open position when said means is released, andmeans operable in response to abnormal circuit conditions to releasesaid actuating means, said handle when moved to close said circuitsresetting said actuating means.

14. A circuit breaker flor selectively `controlling either of twocircuits comprising a frame, two sets of contacts, a switch membermounted solely on said frame and movable to selectively close either setof contacts, manual means for moving said switch member to'selectivelyclose said sets of contacts, means mounting said two sets of contactssubstantially in line with the plane of movement of said manual means,releasa'ble trip means biased to tripping position and operable whenreleased to cause automaticv opening of said sets of contacts, and atrip device operable in response to abnormal conditions in whichevercircuit is closed to release said trip means and cause automatic openingof the corresponding set of contacts, said manual means when moved toselectively close said sets'of contacts resetting said trip means.

STANLEY J

